1. Field of the Invention
The present invention relates to a can opener, more particularly a can opener, which has a single handle, and which is relatively easy to assemble, and can be manufactured with necessary precision relatively easily.
2. Brief Description of the Prior Art
Can openers that have handles operable in laid-down position and are used for cutting the annular sides of cans are among various can openers commercially available. Can openers that have handles operable in laid-down position and are used for cutting the annular sides of cans can be made to consist of a single handle.
Referring to FIG. 6, a popular conventional can opener 2 with a single handle includes a handle 21, a cutting wheel 22, a transmission shaft 23, and a rotary lever 26. There are U-shaped rod 24, and a curved projection 25 provided on an inner side of a front end of the handle 21, which are to be pressed against corresponding parts of a can to locate the handle 21. The cutting wheel 22 extends out between the U-shaped rod 24 and the curved projection 25 from the inner side of the handle 21. The transmission shaft 23 is passed through the front end of the handle 21. Connected to the inner end of the transmission shaft 23 is the traction wheel 231, which is to be pressed against an inner side of an end cover of a can for making the can to move relative to the cutting wheel 22 when the rotary lever 26 is operated; the rotary lever 26 is connected to the other end of the transmission shaft 23 so that the user can turn the rotary lever 26 to effect rotation of the shaft 23 and the traction wheel 231. Thus, when the rotary lever 26 is turned, a can engaged with the can opener is forced to move relative to the cutting wheel 22, and an upper annular side of the can is severed by means of the cutting wheel 22.
Referring to FIG. 7, an exploded perspective view of the above can opener, formed on the front end of the handle 21 is a stepped hole 211 for the shaft 23 to pass through; the stepped hole 211 has a bigger inner end for holding a sleeve 232 and a spring 233. The transmission shaft 23 has a locating hole 234 formed across the outward end thereof; the locating hole 234 is formed by means of drills. Fitted around the outward end of the shaft 23 is a hexagonal member 27, which has opposite gaps 271 at an outward end, and slopes 272 facing the gaps 271. The rotary lever 26 has a hexagonal hole 261 in the middle. There are adjustment pads 236 fitted around the shaft 23 and disposed between the outward side of the handle 21 and the hexagonal member 27 for adjusting the distance between the traction wheel 231 and the blade of the cutting wheel 22 with. After the shaft 23 is passed through the spring 233, the sleeve 232, the stepped hole 211, the adjustment pads 236, and the hexagonal member 27, an adjustment pin 235 is passed through the locating hole 234 of the shaft 23 with two ends thereof being held in the opposite gaps 271 of the hexagonal member 27; referring to FIGS. 8, and 9, if the lever 26 is not turned in the cutting direction, the ends of the adjustment pin 235 will be pressed against lower ends of the slopes 272 of the hexagonal member 27 owing to the spring 233. The rotary lever 26 is joined to the hexagonal member 27 at the hexagonal hole 261. Thus, the traction wheel 231 can be made to stay in a not-action position farther away from the cutting wheel 22 when the ends of the adjustment pin 235 are pressed against the lower ends of the slopes 272.
When the U shaped rod 24 and the cutting wheel 22 are pressed against corresponding portions of a can and when the lever 26 is turned in the cutting direction, i.e. counterclockwise in the FIGS., the hexagonal member 27 will first be turned relative to the adjustment pin 235 so that the ends of the adjustment pin 235 are pressed against the higher ends of the slopes 272 instead, and in turn, the shaft 23 is made to slide outwards and the traction wheel 231 is pressed against the inner side of the annular portion of the can cover. Thus, the upper annular lateral side of the can can be severed by means of the cutting wheels 22 when the user continues to turn the lever 26 in the cutting direction to move the can relative to the cutting wheel 22.
This can opener is convenient to use, however, it is found to have disadvantages as follows:
1. It is relatively difficult to drill across the shaft 23 to make the locating hole 234 because the shaft 23 is cylindrical, and drills used in the drilling process are prone to be diverted or to break, causing defect rate to increase and endangering the workers. Consequently, the manufacturing cost is relatively high.
2. The shaft 23 is usually made of relatively hard steel that has large proportion of carbon; therefore, it is difficult to make the locating hole 23 in predetermined position with precision.
3. Should the locating hole 234 be not formed in such a manner that an axis thereof and that of the shaft 23 intersect and perpendicular to each other, those portions of the shaft 23 that are beside the locating hole 234 will not be the same, and strength of the shaft 23 is reduced. And, the locating hole 234 is prone to be formed off the predetermined position. Consequently, workers have to spend time in finding adjustment pads with suitable thickness for offsetting the errors, otherwise the traction wheel 23 can""t be engaged with the inner side of the annular portion of the can cover with proper pressure, and the smoothness of the cutting operation can be reduced.
4. It is necessary to round off two ends of the locating hole 234 for allowing the adjustment pin 235 to be inserted through the locating hole 234 easily. However, a drill used for the rounding-off process is prone to be diverted because the ends of the locating hole 234 curve together with the lateral side of the shaft 23; when the drill comes into contact with the convexly curved portions of the ends of the hole 234, it can""t move smoothly. In addition, the ends of the locating hole 234 have to be polished manually after the rounding-off process, causing increase of manufacturing cost. The adjustment pin 235 is very smooth on the surface therefore it is likely to fall off the locating hole 234 in assembly causing trouble to the laborers.
It is a main object of the present invention to provide a single-handle can opener, which is equipped with an adjusting mechanism capable of being easily manufactured and assembled.
It is another object of the present invention to provide a single-handle can opener, which can be provided with precision in respect of the space between the cutting wheel and the traction wheel, either in the action position or in the not-action position.
It is yet another object of the present invention to provide a single-handle can opener, of which the adjusting mechanism can""t become loose during the course of the rotary lever is turned in the cutting direction to open a can.
The present can opener is equipped with an adjustment element instead of the pin of the prior art, and the shaft is formed with threads on the outward end portion instead of the locating hole of the prior art. The adjustment element is screwed onto the outward end of the transmission shaft, and has two wing portions in contact with the sloping portions of the hexagonal member so that the sloping portions can effect reduction of the space between the traction wheel and the cutting wheel upon rotational operation of the lever in the cutting direction.